Single point insulin sensitivity estimator index is associated with predominance of atherogenic small, dense low-density lipoprotein cholesterol particles in Korean obese adults: a retrospective study.

Background: Insulin resistance (IR) influences lipid metabolism, particularly small dense low-density lipoprotein cholesterol (sdLDL-C), a key feature of diabetic dyslipidemia and a predictor of cardiovascular disease. The single-point insulin sensitivity estimator (SPISE) index is an effective tool for assessing IR. This study explored the relationship between the SPISE index and average low-density lipoprotein cholesterol (LDL-C) particle size in obese Korean adults.

Methods: Cardiovascular risk was assessed in 161 obese individuals. The participants were divided into three groups based on SPISE index tertiles. Steiger's Z test was used to assess the differences in correlation coefficients among various IR indices and average LDL-C particle size. Multivariate linear regression models were used to determine the independent association between the SPISE index and average LDL-C particle size. Receiver operating characteristic (ROC) curves established the SPISE index cut-off for sdLDL-C particle dominance.

Results: The SPISE index was positively correlated with mean LDL-C particle size after adjusting for confounders. It demonstrated a stronger independent association with average LDL-C particle size (r=0.679, P<0.001) than with fasting insulin, the homeostatic model assessment for IR, and the quantitative insulin sensitivity check index (P<0.001 for all). ROC analysis identified an optimal SPISE index cutoff for sdLDL-C predominance of 4.955, with an area under the curve of 0.745.

Conclusion: Our findings indicate a direct correlation between the SPISE index and average LDL-C particle size, suggesting that the SPISE index may complement labor-intensive IR indices and sdLDL-C measurement techniques for estimating IR-induced sdLDL-C predominance.